The invention is in the field of devices which provide breathable air to workers and others who are operating under conditions in which the ambient air is not suitable for breathing. Such breathing apparatus fall into three categories according to the level of danger, and the type of danger, at the working area. First, a simple mask respirator having a filter can be used in areas high in dust or other particulate matter, there being no collateral equipment required other than simply the filter and the mask.
Another respiratory protection unit is the self-contained breathing apparatus which must be used according to Federal Regulations in any area in which the ambient air is so poisonous that the user would die in the event his supply of artificial air were suddenly terminated. The third type of breathing equipment is the type to which this patent application pertains, namely, in-line breathing equipment which is used where continuous breathing of ambient air could harm the worker, such as in a spray-painting booth, in certain areas of steel mills, at sand blasting operations, and elsewhere. In these locations temporary deprivation of the artificial air would not result in death, but continued breathing of the ambient air would most certainly result in lung damage.
Units of this latter category provide air through hoses or lines from a remote source. These systems at one time were commonly hoses and masks hooked to the existing compressed air tank and for power in the factory, at the paint booth, at the sandblasting site, etc. However, a few years ago it was discovered that lubricating oil in the cylinders of these high-pressure compressed air pumps was oxidizing into carbon monoxide due to abnormal heat generated by worn pistons and cylinders in old systems. This was believed to have caused many deaths formerly believed due to heart failure, and as a result of this discovery, stringent rules have been promulgated requiring different filters and chemical and electrical alarms, some with automatic shut-off features.
High pressure systems with these safety devices on them would appear to provide the answer to in-line breathing equipment requirements, but for several reasons this is not the case. First, the rough wear the equipment is subject to may disable the alarm system without anyone being aware of it. Also, sometimes an audio alarm would be triggered without being heard by the user, who may be working in an environment high in ambient noise.
Ironically, even when the safety equipment is working perfectly, it can cause real problems on the job site, because if a carbon monoxide sensor is triggered, it is often impossible to isolate the cause of it, and safety inspectors will not permit re-mobilization of the equipment without correcting the malfunction.
To avoid all these problems, the inventor of the instant machine developed an in-line breathing apparatus that used a high-volume, low-pressure oil-less centrifugal pump which eliminated all of the safety problems, and thus all of the problems with safety equipment inherent in the high pressure systems. These systems did, and still do, work quite well. There has, however, heretofore been a practical problem with the low-pressure units, namely, that of air conditioning the breathable air.
High pressure systems deliver air to the vicinity of the user at elevated temperatures due to undissipated heat compression, but by use of a vortex tube a few inches from the face mask, a cooling effect can be implemented. However, the vortex effect requires about 65 pounds of pressure to operate, a pressure level impossible to achieve economically in centrifugal oil-less pumps. Thus, it is the goal of the invention of the hereindescribed apparatus to provide, with the use of a low-pressure oil-less pump, air conditioned air at the face mask.